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Hi Matevz, Andreas is right in that you can get that effect with async reading. Though it can be avoided with a better algorithm which, unfortuantely, wasn't used. So, yes, set the cache to zero for xrdcp, though I would be interested in seeing what effect it has on transfer rate with a single source as well as multiple sources. Andy On Tue, 13 Nov 2012, Matevz Tadel wrote: > Thanks Andy, Andreas! > > Andreas told me this is a feature of async reading and that it gets > sequential if one sets readcachesize to 0. > > Funny that I never printed offsets before :) > > Cheers, > Matevz > > On 11/13/12 10:04, Andrew Hanushevsky wrote: >> Hi Matevz, >> >> This is a known problem. Yes, it bizzare but it is what it is. We will have >> to >> wait for 4.0 when we deploy the new client and the new xrdcp which should >> solve >> this problem. I agree, it's a real problem. >> >> Andy >> >> On Mon, 12 Nov 2012, Matevz Tadel wrote: >> >>> Hi, >>> >>> I'm testing the monitoring collector extension that is capable of storing >>> full >>> access details into a root tree. Running a simple xrdcp I realized that >>> xrdcp >>> first copies data at offset of 8MB and only then the beginning of the >>> file. >>> >>> t ~ time since file open >>> l ~ length of request >>> o ~ offset >>> >>> // file_len=4983779 >>> SXrdIoInfo::Dump() N_reqs = 2, N_vec_read_subreqs = 0 >>> 0 Read t=2 l=483 o=4983296 >>> 1 Read t=4 l=4983296 o=0 >>> >>> // file_len=9311384 >>> SXrdIoInfo::Dump() N_reqs = 2, N_vec_read_subreqs = 0 >>> 0 Read t=2 l=922776 o=8388608 >>> 1 Read t=4 l=8388608 o=0 >>> >>> This is even funnier for a larger file (~400MB) ... the first 8MB >>> (offset=0) >>> are read after 238MB are already read, see below, entry 60. >>> >>> What's the secret here? :) >>> >>> Cheers, >>> Matevz >>> >>> // file_len=428002641 >>> SXrdIoInfo::Dump() N_reqs = 102, N_vec_read_subreqs = 0 >>> 0 Read t=5 l=4194304 o=8388608 >>> 1 Read t=10 l=4194304 o=12582912 >>> 2 Read t=20 l=4194304 o=16777216 >>> 3 Read t=35 l=4194304 o=20971520 >>> 4 Read t=45 l=4194304 o=25165824 >>> 5 Read t=55 l=4194304 o=29360128 >>> 6 Read t=65 l=4194304 o=33554432 >>> 7 Read t=75 l=4194304 o=37748736 >>> 8 Read t=85 l=4194304 o=41943040 >>> 9 Read t=95 l=4194304 o=46137344 >>> 10 Read t=105 l=4194304 o=50331648 >>> 11 Read t=115 l=4194304 o=54525952 >>> 12 Read t=130 l=4194304 o=58720256 >>> 13 Read t=140 l=4194304 o=62914560 >>> 14 Read t=155 l=4194304 o=67108864 >>> 15 Read t=165 l=4194304 o=71303168 >>> 16 Read t=170 l=4194304 o=75497472 >>> 17 Read t=180 l=4194304 o=79691776 >>> 18 Read t=190 l=4194304 o=83886080 >>> 19 Read t=205 l=4194304 o=88080384 >>> 20 Read t=215 l=4194304 o=92274688 >>> 21 Read t=225 l=4194304 o=96468992 >>> 22 Read t=240 l=4194304 o=100663296 >>> 23 Read t=255 l=4194304 o=104857600 >>> 24 Read t=260 l=4194304 o=109051904 >>> 25 Read t=265 l=4194304 o=113246208 >>> 26 Read t=275 l=4194304 o=117440512 >>> 27 Read t=285 l=4194304 o=121634816 >>> 28 Read t=295 l=4194304 o=125829120 >>> 29 Read t=305 l=4194304 o=130023424 >>> 30 Read t=315 l=4194304 o=134217728 >>> 31 Read t=325 l=4194304 o=138412032 >>> 32 Read t=335 l=4194304 o=142606336 >>> 33 Read t=345 l=4194304 o=146800640 >>> 34 Read t=360 l=4194304 o=150994944 >>> 35 Read t=370 l=4194304 o=155189248 >>> 36 Read t=375 l=4194304 o=159383552 >>> 37 Read t=385 l=4194304 o=163577856 >>> 38 Read t=390 l=4194304 o=167772160 >>> 39 Read t=400 l=4194304 o=171966464 >>> 40 Read t=405 l=4194304 o=176160768 >>> 41 Read t=420 l=4194304 o=180355072 >>> 42 Read t=425 l=4194304 o=184549376 >>> 43 Read t=435 l=4194304 o=188743680 >>> 44 Read t=445 l=4194304 o=192937984 >>> 45 Read t=455 l=4194304 o=197132288 >>> 46 Read t=465 l=4194304 o=201326592 >>> 47 Read t=475 l=4194304 o=205520896 >>> 48 Read t=485 l=4194304 o=209715200 >>> 49 Read t=495 l=4194304 o=213909504 >>> 50 Read t=505 l=4194304 o=218103808 >>> 51 Read t=515 l=4194304 o=222298112 >>> 52 Read t=525 l=4194304 o=226492416 >>> 53 Read t=535 l=4194304 o=230686720 >>> 54 Read t=540 l=4194304 o=234881024 >>> 55 Read t=550 l=4194304 o=239075328 >>> 56 Read t=560 l=4194304 o=243269632 >>> 57 Read t=575 l=4194304 o=247463936 >>> 58 Read t=580 l=4194304 o=251658240 >>> 59 Read t=590 l=4194304 o=255852544 >>> 60 Read t=605 l=8388608 o=0 >>> 61 Read t=625 l=4194304 o=260046848 >>> 62 Read t=635 l=4194304 o=264241152 >>> 63 Read t=645 l=4194304 o=268435456 >>> 64 Read t=655 l=4194304 o=272629760 >>> 65 Read t=665 l=4194304 o=276824064 >>> 66 Read t=675 l=4194304 o=281018368 >>> 67 Read t=680 l=4194304 o=285212672 >>> 68 Read t=690 l=4194304 o=289406976 >>> 69 Read t=695 l=4194304 o=293601280 >>> 70 Read t=705 l=4194304 o=297795584 >>> 71 Read t=715 l=4194304 o=301989888 >>> 72 Read t=730 l=4194304 o=306184192 >>> 73 Read t=745 l=4194304 o=310378496 >>> 74 Read t=760 l=4194304 o=314572800 >>> 75 Read t=770 l=4194304 o=318767104 >>> 76 Read t=780 l=4194304 o=322961408 >>> 77 Read t=790 l=4194304 o=327155712 >>> 78 Read t=800 l=4194304 o=331350016 >>> 79 Read t=810 l=4194304 o=335544320 >>> 80 Read t=820 l=4194304 o=339738624 >>> 81 Read t=825 l=4194304 o=343932928 >>> 82 Read t=835 l=4194304 o=348127232 >>> 83 Read t=850 l=4194304 o=352321536 >>> 84 Read t=855 l=4194304 o=356515840 >>> 85 Read t=870 l=4194304 o=360710144 >>> 86 Read t=880 l=4194304 o=364904448 >>> 87 Read t=895 l=4194304 o=369098752 >>> 88 Read t=905 l=4194304 o=373293056 >>> 89 Read t=915 l=4194304 o=377487360 >>> 90 Read t=925 l=4194304 o=381681664 >>> 91 Read t=935 l=4194304 o=385875968 >>> 92 Read t=940 l=4194304 o=390070272 >>> 93 Read t=950 l=4194304 o=394264576 >>> 94 Read t=970 l=4194304 o=398458880 >>> 95 Read t=975 l=4194304 o=402653184 >>> 96 Read t=985 l=4194304 o=406847488 >>> 97 Read t=995 l=4194304 o=411041792 >>> 98 Read t=1005 l=4194304 o=415236096 >>> 99 Read t=1010 l=4194304 o=419430400 >>> 100 Read t=1025 l=4194304 o=423624704 >>> 101 Read t=1030 l=183633 o=427819008 >>> >>> ######################################################################## >>> Use REPLY-ALL to reply to list >>> >>> To unsubscribe from 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